Hot Water Reservoir and Small Hot Water Reservoir

ABSTRACT

A hot water storage arrangement having an electronic control unit, by means of which various modes of operation of the storage arrangement can be set. Those modes of operation can represent a normal mode of operation (at a setpoint temperature of between 30° C. and 100° C.), a frost protection mode of operation (at a temperature &lt;10° C. and &gt;1° C.), a time switch mode of operation (in which it is possible to set times of different setpoint temperatures with an adjustable time switch), an ECO mode of operation (in which an electronic temperature limit of between 30° C. and 55° C. is set), a hygiene mode of operation (in which a periodic increase in temperature of ≥55° C. is set) and/or and run-dry detection mode of operation (in which a temperature difference between a first temperature and a second temperature after heating of the hot water storage arrangement is ascertained).

The present application claims priority from International Patent Application No. PCT/EP2018/056221 filed on Mar. 13, 2018, which claims priority from German Patent Application No. DE 10 2017 105 226.7 filed on Mar. 13, 2017, the disclosures of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

It is noted that citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.

The present invention concerns a hot water storage arrangement and a small hot water storage arrangement.

Hot water storage arrangements have a storage tank and a heating element with which the water in the storage arrangement can be heated.

Small hot water storage arrangements are typically of a volume of less than 15 liters and serve as compact hot water appliances which are used where smaller amounts of hot water are frequently required. In that case those small storage arrangements can be connected for example to a 230 V connection. Such a small storage arrangement typically has a heating element for heating the water in the storage arrangement.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a (small) hot water storage arrangement and a method of controlling a (small) hot water storage arrangement, with which the hot water storage arrangement can be operated more efficiently.

Thus there is provided a small hot water storage arrangement comprising a storage tank for water of a volume of <15 l, a heating unit for heating the water in the storage tank and an electronic control unit. The electronic control unit can activate at least two modes of operation of the small storage arrangement. The electronic control unit is adapted to activate a normal mode of operation with a setpoint temperature of between 30° and 100° C., a frost protection mode of operation, a time switch mode of operation, an eco mode of operation, a hygiene mode of operation and/or a run-dry detection mode of operation. The modes of operation can be activated in parallel (for example the normal mode of operation and the run-dry detection mode of operation) or sequentially (for example the normal mode of operation and the frost protection mode of operation or the normal mode of operation or ECO mode of operation and the hygiene mode of operation).

According to an aspect of the present invention the water in the storage tank in the hygiene mode of operation is heated daily at least once for half an hour to at least 65° C. or once in the week to at least 70° C.

According to an aspect of the present invention the time switch mode of operation has adjustable switch-off and switch-on times and an adjustable comfort temperature and a reduction temperature.

According to an aspect of the present invention the hygiene mode of operation can also be activated when the ECO mode of operation is activated.

According to a further aspect of the present invention the electronic control unit is adapted to activate a boiling water mode of operation at which a temperature of the water in the storage tank is kept in the proximity of the boiling point.

The invention also concerns a method of controlling a small hot water storage arrangement with a storage volume of <15 l and at least two modes of operation. One of the modes of operation of the small storage arrangement is activate by an electronic control unit. The modes of operation can represent a normal mode with a setpoint temperature of between 30° C. and 100° C., a frost protection mode, a time switch mode, an ECO mode, a hygiene mode and/or a run-dry detection mode.

According to a further aspect of the present invention the hygiene mode of operation is activated once weekly to heat the water within the storage tank to at least 70° C.

The invention also concerns a hot water storage arrangement comprising a storage tank for water, a heating unit for heating water in the storage tank, and an electronic control unit which is adapted to activate a normal mode of operation with a setpoint temperature of between 30° C. and 100° C., a frost protection mode of operation, a time switch mode of operation and/or a run-dry detection mode of operation. The control unit is adapted to activate at least two of the modes of operation.

According to a further aspect of the present invention the electronic control unit is further adapted to activate an ECO mode of operation and . . . . The hot water storage arrangement according to the invention has an electronic control unit, by means of which it is possible to set various (at least two) modes of operation of the storage arrangement. Those modes of operation can represent a normal mode of operation (at a setpoint temperature of between 30° C. and for example 100° C.), a frost protection mode of operation (at a temperature <10° C. and >1° C.), a time switch mode of operation (in which it is possible to set times of different setpoint temperatures with an adjustable time switch), an ECO mode of operation (in which an electronic temperature limit of between 30° C. and 55° C. is set), a hygiene mode of operation (in which a periodic increase in temperature of ≥55° C. to 110° C. is set) and/or and run-dry detection mode of operation (in which a temperature difference between a first temperature and a second temperature after heating of the hot water storage arrangement is ascertained).

According to an aspect of the invention the small storage arrangement typically has an insulated tank of a volume of ≤15 liters. In addition the small storage arrangement has an inlet, an outlet, an electrical heating element, a temperature control unit for setting the setpoint temperature and optionally a mechanical safety temperature limiter. Furthermore the storage arrangement has an electronic control unit for setting the respective mode of operation.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages and embodiments by way of example of the invention are described in greater detail hereinafter with reference to the drawings.

FIG. 1 shows a time-temperature chart of the small storage arrangement in a normal mode of operation.

FIG. 2A shows a graph to illustrate the relationship between the time of day and the temperature in a small storage arrangement in a time switch mode of operation.

FIG. 2B shows a graph to diagrammatically illustrate a mode of operation with a daily reduction in the hot water temperature for a small storage arrangement.

FIG. 3 shows a graph to diagrammatically illustrate a mode of operation with a daily reduction and only workday comfort heating.

FIGS. 4A and 4B respectively show graphs to illustrate an individual time program mode of operation.

FIGS. 5A and 5B each show a graph to illustrate an ECO mode of operation (with a hygiene function).

FIGS. 6A and 6B show a graph to illustrate a run-dry protection mode of operation.

FIG. 7 shows a block circuit diagram of a hot water storage arrangement according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements which are conventional in this art. Those of ordinary skill in the art will recognize that other elements are desirable for implementing the present invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein.

The present invention will now be described in detail on the basis of exemplary embodiments.

According to the invention there is provided a hot water storage arrangement having an inlet, an outlet, a heating unit and an electronic control unit.

According to an aspect of the invention the hot water storage arrangement has a tank of a volume of ≤15 liters. According to a further aspect of the invention the storage tank can also be larger.

FIG. 1 shows a time-temperature chart of the small storage arrangement in a normal mode of operation. In the normal mode the electronic control unit controls the electrical heating unit of the (small) hot water storage arrangement in such a way that the water in the storage arrangement is controlled in accordance with a set setpoint temperature T_(setpoint) in the limits of hysteresis. The setpoint value can be set by actuating buttons on the small storage arrangement from 7° C. (frost protection) to 30° C. to 85° C. in 0.5° C. steps. Alternatively the setpoint temperature can also be set to 100° C. or 110° C. To provide boiling water the temperature of the water in the storage arrangement can be kept in the proximity of the boiling point.

FIG. 2A shows a graph to illustrate the relationship between the time of day and the temperature in a (small) storage arrangement in a time switch mode of operation. In that mode it is possible to select various sub-programs. In addition it is possible to set a comfort temperature T_(comfort) and a reduction temperature T_(reduction). Furthermore it is possible to set time intervals for the reduction in temperature. By virtue of a daily reduction in the temperature of the storage arrangement it is possible to reduce the energy consumption of the storage arrangement without the user suffering from loss of comfort.

Thus for example a sub-program in the time switch mode of operation can represent a program for a private home (see FIG. 2B) so that the water temperature is kept for example in the region of the comfort water temperature equal to 65° C. between 6.00 and 18.00 and for the remaining time a reduction temperature of 45° C. is selected. The comfort temperature, the reduction temperature and the switching-on and switching-off process can be selected by means of a menu. FIG. 2B provides in particular an illustration of the switching-on and switching-off times of the comfort and reduction mode.

FIG. 3 shows a graph to diagrammatically illustrate a mode of operation with a daily reduction in the hot water temperature for a (small) storage arrangement. FIG. 3 also shows a time switch mode of operation, wherein that mode can be selected in particular in an office. In that respect for example the temperature can be selected to be the reduction temperature for example on Saturday and Sunday. Otherwise it is possible to set a comfort temperature of 65° C. between 6.00 and 18.00 and a reduction temperature can be selected for between 18.000 and 6.00.

FIGS. 4A and 4B each other graphs to illustrate an individual time program mode of operation. FIG. 4 also shows a time switch mode of operation which however can be individually implemented. In particular in that case switching-on and switching-off can be controlled in dependence on day and in dependence on time. Switching-on and switching-off can be set to be differently distributed over the course of the day.

FIGS. 5A and 5B show a graph to illustrate an ECO mode. FIG. 5 shows in particular the ECO mode (with a reduced energy consumption). According to the invention the (small) storage arrangement has an insulated tank to avoid heat losses. For saving energy the temperature of the storage arrangement in the ECO mode of operation (that is to say a mode involving reduced energy consumption) can be reduced for example to 45° C. In that respect however it is to be noted that, in the case of an ongoing reduction in temperature below 60° C. there is the risk of germ formation. Therefore the water within the storage arrangement can be heated at (regular) intervals to ≥60° C., for example for at least 3 minutes at 70° C.

In the ECO mode of operation for example by actuating a button it is possible to restrict the temperature range which can be set, at between 30° C. and 55° C. In addition thereto it is possible to activate a hygiene program to avoid germ formation. For that purpose for example then the water in the storage arrangement can be heated once per day to over 60° C., as shown in FIG. 5A. According to the invention the hygiene program can be started for example at night at 3.00 and can last for half an hour so that the water is heated to for example 65° C. The water in the storage arrangement can then be reduced again to the set setpoint temperature.

According to an aspect of the present invention the hygiene program can heat the storage arrangement once weekly, for example on Saturday night, at 23.58, for example for 0.5 hour, to 73° C., in order thereby to kill microorganisms (germs), as is shown in FIG. 5B. The water in the storage arrangement can then be cooled again to the set setpoint temperature.

For effectively killing off the relevant microorganisms the water temperature should be at least 70° C. At temperatures of around 60° C. growth of the relevant microorganisms is only inhibited. Activation of the hygiene program once per week is advantageous over activation of the hygiene program once per day. In the case of daily activation of the hygiene program the water would have to be heated daily to at least 70° C. That however would be disadvantageous in regard to energy efficiency. Furthermore that could have the result that the water storage arrangement suffers from limescale buildup more quickly. With weekly activation of the hygiene program less lime is advantageously formed in the hot water storage arrangement.

An advantageous time for activation of the weekly hygiene program is for example Saturday at 23.00 (and therewith an increase in the water temperature to 73° C.). That time represents the time at which the hot water storage arrangement is being least used. That applies in particular for commercial use or daycare nurseries for children. It is thus possible to ensure that a tap is not opened by mistake while the hygiene program is activated and the water has thus been heated to 73° C. By virtue of the above-mentioned selected time for activation of the weekly hygiene program it is possible to provide a period which is long as possible, until the next regular tap opening process occurs.

In the case of private use a tap is typically used on a Sunday later than on working days, so that there is more time for cooling of the stored water, between hygiene heating and use.

Optionally the time switch mode of operation can not be activated if the ECO mode is activated.

FIGS. 6A and 6B show a graph to illustrate a run-dry protection mode. FIG. 6 shows in particular the run-dry protection mode. Hot water storage arrangements typically have a safety temperature limiter STB which deactivates the heating unit when there is no water in the storage arrangement. The shut-down temperature of the safety temperature limiter is typically between 95° C. and 130° C. and is thus above the maximum possible water temperature. The time for shutting down the heating power can be up to 100 s.

According to the invention there is provided an electronic run-dry protection. The water temperature in the storage arrangement is measured by means of at least one semiconductor temperature sensor (NTC sensor). In the case of a run-dry check (before start-up and/or after any mains interruption) the heating element is heated for for example 20 s and in the following for example 40 s a rise in temperature is detected at the temperature sensor. If there is water in the tank then the temperature will rise only slightly. If however there is no water the temperature will rise more quickly.

According to the invention by comparing the temperatures before and after heating it is possible to determine whether there is water in the tank or not.

If it has been established that there is water in the tank then the heating unit can be activated and the water in tank can be heated.

If however there is no water then the heating operation can be interrupted and a fault message can be output.

According to an aspect of the invention the hot water storage arrangement has a boiling water mode of operation in which the water in the storage arrangement is kept at a temperature close to the boiling point. In particular the hot water storage arrangement can be so regulated that the water in the storage arrangement just does not reach the boiling point.

According to a further aspect of the invention a switching hysteresis for the heating element can be increased or reduced in order to save on energy. In particular there can be an increase in hysteresis, in dependence on the time of day. Furthermore there can be a reduction in hysteresis, in dependence on the time of day, to increase the comfort level. A reduced hysteresis is preferably below 1 K temperature difference, in particular less than 0.5 K or less than 0.2 K. Thus it is particularly advantageous to keep the temperature near the boiling point.

Preferably the hysteresis is reduced, the closer the water temperature comes to the boiling point.

FIG. 7 shows a block circuit diagram of a hot water storage arrangement according to the invention. The hot water storage arrangement 100 has a storage tank 110, a heating unit 120 and an electronic control unit 130. Optionally temperature sensors 140 can be provided in the tank 110.

While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the inventions as defined in the following claims. 

1. A hot water storage arrangement comprising: a storage tank of <15 liters; a heating unit configured to heat water in the storage tank; and an electronic control unit configured to activate at least two modes of operation of the hot water storage arrangement; wherein the electronic control unit is configured to activate at least one mode selected from the group consisting of: a normal mode of operation with a setpoint temperature of between 30° C. and 100° C.; a frost protection mode of operation; a time switch mode of operation; an ECO mode of operation; a hygiene mode of operation; and a run-dry detection mode of operation.
 2. The hot water storage arrangement as set forth in claim 1; wherein the electronic control unit is configured to activate the hygiene mode, in which the water in the storage tank is heated daily at least once for half an hour to at least 65° C., at least once in the week to >70° C., or a combination thereof.
 3. The hot water storage arrangement as set forth in claim 1; wherein the electronic control unit is configured to activate the time switch mode, which permits adjustable switch-off and switch-on times and an adjustable comfort and reduction temperature.
 4. The hot water storage arrangement as set forth in claim 1; wherein the electronic control unit is configured to activate the hygiene mode of operation as a result of activation of the ECO mode of operation.
 5. The hot water storage arrangement as set forth in claim 1; wherein the electronic control unit is configured to activate a boiling water mode of operation at which a temperature of the water in the storage tank is kept in the proximity of the boiling point.
 6. A method of controlling a hot water storage arrangement of a storage volume of <15 liters, which has at least two modes of operation, comprising the steps: activating at least one mode of operation of the hot water storage arrangement by an electronic control unit; wherein the at least one mode of operation is selected from the group consisting of: a normal mode of operation with a setpoint temperature of between 30° C. and 100° C.; a frost protection mode of operation; a time switch mode of operation; an ECO mode of operation; a hygiene mode of operation; and a run-dry detection mode of operation.
 7. The method of controlling a hot water storage arrangement as set forth in claim 6; wherein the hygiene mode of operation is activated once weekly to heat the water within the hot water storage arrangement to at least 70° C.
 8. The method of controlling a hot water storage arrangement as set forth in claim 7; wherein the weekly activation of the hygiene mode of operation is effected on Saturday evening.
 9. A hot water storage arrangement comprising: a storage tank configured to store water; a heating unit configured to heat water in the storage tank; and an electronic control unit configured to activate modes of operation,including; a normal mode of operation with a setpoint temperature of between 30° C. and 100° C.; a frost protection mode of operation; a time switch mode of operation; and a run-dry detection mode of operation; wherein the electronic control unit is configured to activate at least two of the modes of operation of the hot water storage arrangement in parallel or sequentially.
 10. A hot water storage arrangement as set forth in claim 9; wherein the electronic control unit configured to activate further modes of operation, including: an ECO mode of operation; and a hygiene mode of operation.
 11. A hot water storage arrangement as set forth in claim 9; wherein the hot water storage arrangement has a water storage tank of <15 liters.
 12. A method of utilizing the hot water storage arrangement as set forth in claim 9 comprising: activating a boiling water mode of operation of the hot water storage arrangement in which a temperature of the water in the storage arrangement is kept in the vicinity of a boiling point of the water. 